Mechanical tools are used by people around the world for increasing the effectiveness of human ability and facilitate nearly every modern convenience. Tools like pliers, nut crackers, winches, car jacks, wire strippers, scissors, and nail clippers are regularly used to manipulate objects in ways that human hands are not capable of. These tools can allow delicate manipulation of objects or manipulation of objects under extreme forces.
Many of the mechanical tools that provide mechanical advantage are fulcrum based tools. The fulcrum based tool concentrates the force that a user is able to apply. Fulcrums operate when force is applied at different distances from a pivot point and convert a long motion of small force into a shorter motion of larger force. Fulcrum based tools, intended for hand use, typically include a handle and a head held in a fixed ratio with a pivot.
Maintaining the fixed ratio between the handle and the head enables force multiplication; however, controlling the tool relies almost entirely on the skill of the operator and when utilized by people of differing physical size and strength, this is not always easy or even possible. This problem can be seen when a work piece is so large that in order to fit it within the head, the handles must be spread apart to an angle that does not allow for easy gripping even with large hands. The same problem can be seen when the work to be accomplished requires extreme forces and even with the mechanical advantage of the fixed ratio, a person may simply not be able to squeeze hard enough, and in the event that they struggle to apply the requisite force, the result will nearly always be completely uncontrollable. Many attempts to resolve this problem have not resulted in a complete or meaningful solution.
One attempt to resolve this problem is to increase the fulcrum length providing more mechanical advantage to the head. This results in a larger tool that can be even more unwieldy and thereby cause physical damage to a work piece. In the event the increased fulcrum length provides enough mechanical advantage new problems arise due to the length of travel required by the larger handles. The larger travel can necessitate the use of two hands eliminating the ability to handle or control the work piece.
Another attempt to resolve this problem is to provide a moveable pivot. These tools are known as tongue and groove pliers and allow the handles to be operated within a comfortable range of motion even with larger work pieces. Improvements to the tongue and groove pliers have included a self-selecting pivot based on the size of the work piece and eliminate the clumsiness of choosing a pivot point setting before beginning work, and while the moveable pivot does make the tool easier to control in one aspect, the moveable pivot fails to solve the problem arising from inadequate mechanical advantage.
Other attempts focus on including ratchets, locks, ergonomic handles and other partial solutions, but have limited applicability and still fail to provide intuitive control, increased mechanical advantage, while allowing for a natural range of motion. All previous attempts have failed to provide a complete solution, but have instead addressed only the ergonomic manifestation of the problem or the mechanical advantage manifestation of the problem but not both. Solutions have been long sought but prior developments have not taught or suggested any solutions, and thus, solutions to these problems have long eluded those skilled in the art.